The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
May. 21, 1996
Filed:
Aug. 15, 1994
Naoki Tatsumi, Shiga, JP;
Daigo Morioka, Shiga, JP;
NEC Corporation, Tokyo, JP;
Abstract
A powder type electroluminescent (EL) device comprises a step-up circuit for charging a capacitive EL element during a charge period, discharge transistor for discharging electric charge from the EL element during a discharge period, a voltage detector for detecting the predetermined voltage of the EL element to generate a charge-up signal, and a control section for starting the discharge period responsive to the charge-up signal. Even if the equivalent capacitance of the EL element decreases or the loss in the EL element increases with an enviromental condition, deterioration in luminous intensity does not arise. Accordingly, a longer life of the EL device can be obtained.